A two-dimensional correlation spectroscopic study to probe the sensitivity of functional groups of “Helixone” membranes to thermal, and irradiation treatments

Abstract

The development of the state of the art hemodialysis membranes requires advanced material characterization to understand membranes functions and ageing mechanisms. Two-dimensional correlation (2D-COS) combined with Fourier Transform Infrared (FTIR) spectroscopies were utilized to probe the changes occurring on thermal, γ-rays and ultra-violet irradiation of polysulfone (PSF)/poly vinyl pyrrolidone (PVP) dialyzer system. The results demonstrated that the sensitivity of PVP decreased in the order: UV→γ-rays →thermal treatments. In addition, among the aromatic bands at 1605, 1595, 1570, 1515, 1505, 1485, 1460 and 1420 cm⁻¹, only the bands at 1485 or 1505 cm⁻¹ increased in intensity with increasing treatment extent, and they changed after all other bands. This was attributed to the increase in molecular orientation of PSF, which occurred after the removal of PVP. Moreover, the increase in intensity for both ether and sulphone groups in all types of treatments support the occurrence of molecular orientation. Furthermore, the decrease in the intensity of aromatic bands at 1605, 1515, 1570, 1595, 1460 and 1420 cm⁻¹ implied the release of some bisphenol-A (BPA) or bisphenol-S (BPS) units. The later was shown to be more sensitive to UV- irradiation than BPA. The results indicated that the haemodialyser is expired not only due to the leaching of PVP, but also degradation of PVP and the formation of succinimide as well as yet to a lesser extent the release of some BPA and PBS units.